Best Free ETF Overlap Tools Compared (2026)

Why the Right Overlap Tool Matters

ETF overlap sounds like a niche topic until you discover that your "diversified" portfolio of four funds has 80% concentration in the same megacap tech stocks. The right tool makes this visible instantly; the wrong tool leaves you guessing from top-10 holdings lists.

The core problem with using a broker's comparison feature or simply eyeballing top holdings is that top-10 lists only capture 20–40% of most ETFs. A fund with 500 holdings has 490 positions your broker comparison tool is ignoring. Weighted overlap — which accounts for every holding's actual weight in the portfolio — is the only number that gives you an accurate picture.

Here are the best free tools for measuring ETF overlap in 2026, evaluated on accuracy, ease of use, and what each does best.

1. etf-checker.org — Best for Quick Weighted Overlap

What it does: Enter any two ETF tickers and instantly see the weighted overlap score — the percentage of portfolio weight the two funds share — along with the count of shared holdings and the top shared positions.

Why it stands out: etf-checker.org uses the minimum-weight method to calculate overlap, which is the most accurate available. For each shared holding, it takes the smaller weight between the two funds and sums those minimums. This gives you the true dollar-for-dollar overlap — how much of your actual investment is duplicated — not just whether a stock appears in both funds.

For example, if Fund A has NVIDIA at 6.6% and Fund B has NVIDIA at 7.7%, the overlap contribution from NVIDIA is 6.6%, not the average of the two. That conservative methodology means the score is not inflated.

The interface is clean and fast. No account required. Covers thousands of U.S.-listed ETFs.

Best for: Quickly checking any specific pair before making a portfolio decision.

Try it: etf-checker.org

2. ETF Research Center (etfrc.com) — Best for Detailed Holdings Breakdown

What it does: ETF Research Center shows weighted overlap by weight, number of overlapping holdings, and the percentage of each fund also found in the other. The free tier shows the top 5 shared holdings; full holdings require a basic free membership.

Key data point it surfaces: It shows "% of Fund A also in Fund B" and "% of Fund B also in Fund A" — two different numbers that reveal the asymmetry. For VTI vs VOO: 17% of VTI is also in VOO, but 100% of VOO is also in VTI. That asymmetry tells you a lot about the relationship.

Limitations: The free tier truncates the overlapping holdings list. Getting the full picture requires registration (free) or a paid subscription for the complete data alongside sector drift analysis.

Best for: Investors who want to see sector drift alongside overlap — how the two funds differ in their sector allocations.

3. MarketXLS ETF Overlap Calculator — Best for Count-Based Comparison

What it does: MarketXLS provides holding-count-based overlap — showing how many stocks are shared and what percentage of each fund's holding count they represent.

For QQQ vs SPY, it reports: "QQQ and SPY share 86 holdings (95.32% of QQQ, 52.22% of SPY)." That framing — percentage of holdings by count — is useful for understanding structural similarity but is not the same as weighted overlap.

Important distinction: Count-based overlap can be misleading. SCHD and VTI share ~95 holdings (98% of SCHD's holdings appear in VTI), but the weighted overlap is only 6–7% because those shared stocks are minor VTI positions. MarketXLS's count metric would suggest high overlap; etf-checker.org's weighted metric correctly shows low overlap.

Best for: Getting a quick count-based comparison when you want to understand structural similarity between funds.

4. ETF.com — Best for Comprehensive Fund Data Alongside Overlap

What it does: ETF.com offers side-by-side comparisons covering expense ratios, performance, dividend yield, assets under management, and more. The overlap feature shows holdings comparison but focuses primarily on top holdings rather than complete weighted overlap.

Best for: Comparing funds on all dimensions simultaneously — not just overlap but also cost, performance, and fund quality.

Limitation for overlap: Like most broad comparison tools, it shows top holdings rather than full weighted overlap. Use etf-checker.org for the overlap number and ETF.com for the full fund comparison.

5. Portfolio Visualizer — Best for Multi-Fund Analysis

What it does: Portfolio Visualizer is the most powerful free tool for multi-fund portfolio analysis. While not strictly an overlap tool, it calculates correlation between funds, which is a related but distinct measure.

Correlation tells you how funds move together; overlap tells you how much they share at the holdings level. High overlap almost always produces high correlation, but the reverse is not always true — two funds can be correlated due to macro factors without having the same holdings.

For overlap specifically, Portfolio Visualizer works best as a complement to a dedicated overlap tool rather than a replacement.

Best for: Backtesting portfolio allocations and understanding historical correlation and risk metrics.

6. Bankrate / Investment News Ratings — Best for Oriented Readers

For investors who want a broader guide that compares ETF overlap tools rather than just using them, Bankrate and InvestmentNews publish reviews listing ETF Research Center, ETF.com, and ETF Database as the primary free options. Their coverage is useful for context but these articles don't go deep on the methodology differences between tools.

Which Tool Should You Use?

| Use Case | Recommended Tool | |---|---| | Check overlap for a specific pair quickly | etf-checker.org | | See sector drift alongside overlap | ETF Research Center | | Full fund comparison (costs, performance, holdings) | ETF.com | | Multi-fund portfolio analysis | Portfolio Visualizer | | Count-based holdings similarity | MarketXLS |

For most investors making a specific portfolio decision — "should I hold both VTI and VOO?" or "does adding QQQ to my SPY position actually diversify me?" — etf-checker.org gives you the answer in under 30 seconds with the weighted methodology that most accurately reflects real dollar exposure.

The Overlap Number That Actually Matters

Regardless of which tool you use, prioritize weighted overlap over holding-count overlap. A fund with 500 stocks and a fund with 100 stocks will appear to share "only 20% of holdings by count," but if those 20% shared holdings are the largest positions in both funds, the real dollar overlap could be 60–70%.

The minimum-weight method — which sums the smaller weight for each shared position across both funds — is the right way to measure this. It directly answers the question: "Of every dollar I invest across both funds, what fraction is doing the same work twice?"

That is the number you need to make informed portfolio decisions.